Name: _______________
Date: ___________
Properties of Acids and Bases: A Laboratory Experiment
(modified from Appendix 2.3 in Senior 2 Science: A Foundation for Implementation)
Purpose
There are three goals these experiments will strive to achieve:
1. To classify substances as acids or bases using their characteristic properties.
2. To determine the pH values of the acids and bases used.
3. To examine the reactivity of acids with metals.
Equipment/Materials
 Safety goggles
 Red and blue litmus paper
 Test tubes and test-tube racks
 Indicators (universal indicator, phenolphthalein, bromothymol blue)
 pH test paper
 Eye droppers
 Microtrays
 Acids
o Hydrochloric acid, HCl (6 M)
o Acetic acid, CH3COOH(6 M)
 Bases
o Sodium hydroxide, NaOH (0.5 M)
o Calcium hydroxide, Ca(OH)2 (0.5 M)
 Metals
o copper, zinc, iron and magnesium
Safety
When dealing with acids and bases, always consider safety. Hydrochloric acid and sodium
hydroxide are very corrosive or caustic and will irritate the skin and eyes. Please follow all
the directions carefully, wear your goggles at all times and notify the teacher if there are
any spills that need to be cleaned up immediately. If you spill any acids or bases on your
skin, in your eyes or on your clothes, wash with cold water right away and tell the teacher.
**Note: Any fooling around in the laboratory is not acceptable. If you are being
disruptive, you will be asked to leave without question.
Procedure
 Please work in lab groups of 2-3 people. Assign one person the task of reading the
directions, the other of conducting the experiment and the third of recording results.
Please made as many observations as you can on your paper.
There are three stations set up around the classroom, one for each part of this lab. At each
station, there are three substations with all the material you need to conduct this part of the
experiment. Please read all the directions very carefully before completing each step. Do not
skip steps. If you are unsure what to do, ask the teacher. Once you are finished at your station,
make sure the area is clean and move on to the next open station. Record all your results in the
data tables given.
Part A: Effects of Acids and Bases on Indicators
1. Place five drops of each of the following into separate wells of a microtray: 6M
Hydrochloric acid, 6M acetic acid, 0.5 M sodium hydroxide, and 0.5 M calcium
hydroxide.
2. Using different pieces of clean, dry litmus paper for each solution, dip one end of the
paper into each solution. Record your results in the data table.
3. Repeat step 2 using blue litmus paper. Record your results in the data table.
4. Wash the microtray using the wash bottle and the pail next to the station. Dry with a
paper towel and set aside for the next group.
Part B: Determine the pH range of a Substance
1. Place five drops of each of the following into separate wells of a microtray: 6M
Hydrochloric acid, 6M acetic acid, 0.5 M sodium hydroxide, and 0.5 M calcium
hydroxide.
2. Add two drops of bromothymol blue indicator to each sample well. Record your
observations in a data table.
3. Wash and dry microtray and repeat steps 1 and 2 for phenolphthalein and universal
indicator.
4. Wash and dry microtray and repeat steps 1 and 2 with pH test paper.
Part C: Determine the Reactivity of Acids and Bases with Metals
1. Place a small sample of each metal to be tested in the different wells of a clean, dry
microtray.
2. Use an eyedropper to add five drops of the hydrochloric acid onto each sample of metal.
Note any signs of chemical change and record your observations in a data table.
3. Wash miroctray and repeat steps 1 and 2 using the acetic acid.
Data Collection
Part A
Sample
Reaction with red litmus
paper
Reaction with blue litmus
paper
Hydrochloric acid, HCl
Acetic Acid, CH3COOH
Sodium Hydroxide, NaOH
Calcium Hydroxide,
Ca(OH)2
Part B
Sample
Bromothymol Blue
Phenolphthalein
Universal
indicator
pH paper
Hydrochloric
acid, HCl
Acetic Acid,
CH3COOH
Sodium
Hydroxide,
NaOH
Calcium
Hydroxide,
Ca(OH)2
Part C
Metal
Zinc
Magnesium
Iron
Copper
Reaction with hydrochloric acid
Reaction with acetic acid
Data Analysis
Fill out the table below according to your findings in parts A, B and C.
Remember:
Acids
- Hydrochloric Acid
- Acetic Acid
Tests
Bases
- Sodium Hydroxide
- Calcium Hydroxide
Acid properties
Base properties
Red litmus paper
Blue litmus paper
pH paper
Bromothymol Blue
Phenolphthalein
Universal indicator
Reaction with a metal
Questions (answer on a separate sheet of paper)
1. Can either red or blue litmus paper be used to identify acids? Explain.
2. How accurate are indicators for measuring pH?
3. What signs of change were observed when acids were placed on metals?
4. Did all metals react similarly? Explain how each metal reacted with each acid.
5. List the general properties of acids and bases.
Something to think about…
What were the bubbles in the solution when the metals reacted with the acids? How do you
think we could test to see what kind of gas was being produced in that reaction?